Guardian

HAVING missed last Friday’s flyby of asteroid 1998 QE2, I started searching for footage of the event – and ended up with the “Geeks”.

No, I wasn’t captured and caged. So I didn’t have to hold out a bone to deceive a blind witch, like someone did in a fairy tale.

Fortunately, there were no wicked witches at the “White House We The Geeks Google + Hangout On Asteroids” – just a Wicked Old U.S. President (lurking somewhere unseen) who refuses to come to Nigeria!

The dictionary in my cell-phone contains two definitions of a geek. One is a carnival performer who does disgusting things. The other is a person with an unusual or odd personality.

I’m sure Obama would prefer the second definition. Anyway, sense-one doesn’t really apply because the programme was quite informative and insightful.

If there were anything “disgusting” about the programme, it was the absence of a black person. The White House, it seems, is going to remain the white house, no matter who happens to be putting up there.

I guess these space buffs think of themselves as “odd,” because the President’s place of abode is not where you’d expect to find a of panel of this kind – with scholars, venture capitalists and space explorers discussing asteroids.

Come to think about it, the presenter is a curiosity piece of sorts. She’s a middle aged white woman who thinks everything about asteroids is “Awesome”. That, at least, is the way it seemed during the first half of the discussion.

Actually, it shouldn’t surprise anyone that asteroids are now being talked up at the White House. Within the past three months, two of these uninvited guests have intruded into Earth’s orbital domain. A third threw a tantrum over Russia and injured 1000 people at Chelyabinsk.

Asteroids, therefore, are “in”.  But while the world may be more conscious of these orbiting bombs, this is due largely to the power of the media and the willingness of authorities in the industrialised nations to go public with the information.

Asteroids are the shards of what would have been a fifth rocky planet, with its orbit lying between Mars and Jupiter. But the gas giant guards its orbital territory jealously – breaking up any smaller body that attempts to form within its gravitational field.

Asteroids are the primitive ruins of this cosmic battle for territory and dominance, which commenced more than four billion years ago, during the formative stages of our solar system, and continues.

Most asteroids still orbit the sun, between Mars and Jupiter. But the gravitational influence of the gas giants has rendered this region dynamic and unstable. In other words, no newcomer is welcome; and the remains of the shattered bodies, the planetesimals, can never be at rest.

Since the solar system formed 4.6 billion years ago, much of this debris has been ejected outward into interstellar space. But quite a large number of these bodies have been – and continues to be – flung inwards, towards the Sun.

Consequently, there are swarms of asteroid fragments orbiting inside the path of Mars, even between Earth and the Sun. Those that come within 1.3 astronomical units (AU) of Earth (such as the Atiras group), or cross its orbital path, are called Near Earth Asteroids (NEA).

“In terms of orbital elements,” NASA notes, “NEOs are asteroids and comets with perihelion distance q less than 1.3 AU. ….The vast majority of NEOs are asteroids, referred to as Near-Earth Asteroids (NEAs). NEAs are divided into groups... according to their perihelion distance (q), aphelion distance (Q) and their semi-major axes (a)”.

Group Description Definition

NECs

Near-Earth Comets

q<1.3 AU,P<200 years

NEAs

Near-Earth Asteroids

q<1.3 AU

Atiras

NEAs whose orbits are contained entirely with the orbit of the Earth (named after asteroid 163693 Atira).

a<1.0 AU,Q<0.983 AU

Atens

Earth-crossing NEAs with semi-major axes smaller than Earth’s (named after asteroid 2062 Aten).

a<1.0 AU,Q>0.983 AU

Apollos

Earth-crossing NEAs with semi-major axes larger than Earth’s (named after asteroid 1862 Apollo).

a>1.0 AU,q<1.017 AU

Amors

Earth-approaching NEAs with orbits exterior to Earth’s but interior to Mars’ (named after asteroid 1221 Amor).

a>1.0 AU, 1.017<q<1.3 AU

PHAs

Potentially Hazardous Asteriods: NEAs whose Minimum Orbit Intersection Distance (MOID) with the Earth is 0.05 AU or less and whose absolute magnitude (H) is 22.0 or brighter.

MOID<=0.05 AU, H<=22.0

•Courtesy NASA, Near Earth Asteroid Programme

• To be Continued.